Installing an Under Cabin Hatch

So, first of all know that this isn’t easy, but totally doable by a novice like me. This is just how I did the work; you may know a better way or should check with someone else on this as there are many ways to do this project. I have some pictures at the end of the article to help aid your understanding. Good Luck, it’s well worth it!

First you’ve got to make or get a pan for the under cabin hatch. I recommend getting one made out of the mold that one of the fleet members has. I spent the previous winter making a pan by eye, and it would have worked, but it was heavy and not as good looking as the one made from the mold. I bought the pan while we where down at Nationals this past October for $225, and it was worth every penny. If you’d like one get in touch with me and I will get one on its way.

Installation:

Before you get started take the pan you have and prime and paint the inside to seal it up so it doesn’t soak in water over time and get heavier. This should make it so plants don’t grow as quickly inside as well.

These are the materials I got together before hand;

Extendable pole (for prying the pan up into the cabin top, holding it in place)

4 – 4’ sticks for prying things in place

2 – 3’ 2x4’s (for molding to the cabin top to hold the glass in place)

Polyester resin (for filling holes and making the outside lip so you can gelcoat it)

West Systems Epoxy with catalyst for the temperature you’ll be working in (for the interior stuff you will paint)

Adhesive additive for the epoxy

3 - 1”x1”x3’ pieces of wood to form the exterior lip

Blue Evercoat filler

Masking tape

Packing Tape

Duct Tape (can’t do anything without Duct tape, come on!)

Keg cups for mixing (careful, they burn when the resin sets up)

Mixing sticks

Masking plastic (I used 3M masking plastic)

A grinder with rough sand paper

A Vacuum

Jig Saw (Sabre Saw)

Random Orbital Sander with 60 to 120 grip paper

Drill and drill bits

Fein Saw (borrow one if you can, it’s a great tool for this)

Drehmel tool or similar

Screwdrivers

Primer and whatever color paint you want to paint the pan once it’s installed.

Different fiberglasses, I used 4” regular tape and the thick sheets cut into 4” strips

A box of plastic gloves

Probably other things I didn’t use or forgot as well.

Getting Started:

Take off the old system, rails on the deck and the wood in the cockpit that holds the slat in place. Save the slat, plastic companion cover and the wood as you can re-use them in the new system. I would suggest sanding the wood down now and start re-varnishing it so it’s ready to install when you’re done.

Take the pan and put it up against the cabin top from the inside and wedge it in place with the extendable pole. By doing this you can then take a pen and outline it on the cabin top and you can measure the opening to see if you need to cut back the existing lip or if you need to add to it. I had to add to mine which I think is best so the new lip has some structure to attach to, so if you need to cut your lip back I would suggest cutting it a bit big by about 3/16”. While the pan is in measure down from the lip to the pan rails and write this number down. On mine it was 1”, you’ll need this later.

Now the dusty part, take that grinder with the rough sandpaper (I used 36 grit) and grind away all the paint or gelcoat on the cabin roof out about 3” from where the outline of the pan is. This will give you good open fiberglass and great contact for later fiberglassing. Be careful not to grind too much as it is easy to go through. When you done inside you need to grind away the gelcoat on the existing lip on the outside where you’re going to fiberglass the new drop down lip in place due to the hatch being lower by about 5/8” than the existing lip (at least on my boat, yours may be different). When done, Vacuum, Vacuum, Vacuum, I tried to clean after every step as it’s a small space you’re working in.

Now, take the 3 pieces of wood 1”x1”x3’ and shape them with your saw and sander to fit in place around the companion way opening. Once properly shaped cover them with the packing tape (so the resin doesn’t stick to them) and install them by screwing them in, through the lip, from above about 1/8” bigger than you want the opening to be once you’re done, as the fiberglass will take up this space. Take your drill and drill bit one size bigger than the old holes that held the rails on and drill them out clean. Use small strips of duct tape inside the cabin to block off the clean holes. Take your masking and lay it out inside the boat to catch any resin drips. Cut your 4” fiberglass tape to fit around the lip. I would suggest 3 layers. Then mix up some polyester resin and fill the holes slowly, so as to not create air pockets, from the top, check back on these as your working and fill as needed until they stop sinking. You may have your own system, but what I did was put the tape right into the resin and get it fully soaked, then place it where I wanted around the companion way, smoothing out all 3 layers as best I could, it will be hanging down longer than you need but you can cut this off later when it’s dry. This wasted a lot of resin but should get you full contact on each layer. Clean up and walk away for the night while the resin dries, be sure to not leave an left over catalyzed resin on the boat in the cup as it will get very hot, milt the cup, make a mess and possibly catch on fire. I usually put the resin in a dumpster or out somewhere where it won’t matter if the cup melts and catches on fire.

Day 2; Take out the wood frame you built for the lip and make a look of satisfaction. Get the masking out of the way and get started. Now take that measurement of the distance from the old lip to the pan you wrote down, subtract 1/8” and draw a line around the newly laid fiberglass (ignoring the curve of the cabin top on the front edge) a nice straight line. Take your Fein saw with the bi-metal blade and cut this line. This will allow you to get the pan in place with out touching the new lip; you’ll cut it to fit your hatch thickness later, once the pan is installed.

Now for some fun; take your sander and sand the three outside edges of the pan for adhesion and then clean up again with the vacuum, making sure you vacuum everything you sanded. Take the pan and wedge it back in place. My companionway wall has had a layer of plywood added to it for strength and I had to notch the corners of the layer of plywood to get the rails in place against the fiberglass. I would suggest this as it gave good structural support to the ends of the rails. Once you’ve got it where you want it, lay out some new plastic masking and mix up some Epoxy with the adhesive additive until it’s nice and thick. Using your fingers, finger the mixture in place wherever the pan touches or is close to touching the inside of the cabin top on the sides and where the rail touches the companion way wall, using a bit extra hear for support. On the front of the pan use a good amount of mixture here and make sure it is good and sealed as there is no need for glass on the front edge for structure (I hope at least), just make sure it is adhered and sealed. Carefully crawl out of the boat for the day, you’re done. I went out the front hatch so as to not bump anything. Again, don’t leave the left over hot resin on board.

Day 3; Take out the supporting pole, and clean up again. This next step takes patience as the cabin top is anything but flat and straight, (You can ignore this next part and just try and put the fiberglass in place by hand but gravity may have its way, remember this is just what I did). Take your 2 - 2x4’s and shape them to fit up tight against the cabin top and the pan, this will take time but is worth it. Once done take your small 4’ sticks and cut them so you can wedge the 2x4’s in place tightly. Cover the 2x4’s completely with packing tape and cut the large weave fiberglass sheet into 4” strips, lay enough out on the 2x4’s to cover the area you want glass completely, I had two pieces on each 2x4 but it will depend on how big your strips are.

Now the really messy part; Lay out your masking again and mix up some epoxy, I believe I mixed up about 14 OZ for this step but make sure you have enough. The rest is easy, thoroughly soak the strips with epoxy (I just put them in the container) and then lay them out on the 2x4 and then wedge the whole think in place with the sticks. Do the same thing with the other side and then get out of there, it’s dripping everywhere and stinks, I used the front hatch again. Remember to take the left over hot resin with you.

Day 4; Take out the wood and look at your work. Clean up everything and lay out new plastic masking. At this point I sanded all the edges of the fiberglass smooth and then mixed up another good thick batch of the Epoxy with additive and fingered it in all over the new fiberglass, both to give it good solid structure and to seal any holes or seams. While you leave this to dry you can measure up from the rails of the pan the thickness of your new plastic hatch and cut the opening big enough for the plastic to slide in. At the same time you can cut away a section of the companion way wall so you can slide the plastic cover in from the back. I took my existing piece of plastic from the old top and cut it 1/8” less in width than would fit into the pan on my table saw at home and then slid it in. Once in you can slide it in you can make adjustments to the lip and rails until it runs smooth.

Once all is fit you can remove the plastic hatch cover and take the Blue evercoat filler and use it to smooth out the new lip you made. This stuff dries quickly and sands very easily. Do a few coats until you have everything smooth and ready for gelcoat. Then clean up and head home.

Day 5; Come back and clean up everything again. Then find the center of the drip rail about 3/8” up from the inside bottom edge. Drill a 5/8” hole and then using your drehmel tool with some sand paper, sand this hole out until its flush with the drip rail. Take out the plastic cover and mask off around the two holes and the slots you cut for the plastic cover to come out. Once it was all masked off I took a piece of tape and went across the bottom of the drain hole about 1/32” above it to create a small dam for the epoxy. Coat everything with epoxy to seal it off.

Once done with the epoxy you can get inside and lay out some plastic again. Take your primer and paint the pan and new fiberglass out far enough to cover everything you installed and sanded. Clean up and head home

Day 6; easy day, clean up everything, lay out new plastic and paint a coat of paint over everything. I used Petit EasyEpoxy and was able to do only one coat as it is such thick paint. You may need to do a second coat of paint if the paint you use is thin. Clean up and head home

Day 7; this is when you would mask everything off and spray your gelcoat on the new lip and deck area. I have not done this step as of yet because I am waiting for warmer weather (I did my project the first week of January). I have seen boats do a full H to cover everything, and this looks really good. You can also clean up the legs and just gelcoat the lip around the hatch, its up to you, it’s just a look.

Day 8; Put it all back together, clean up and remove all the masking tape. Make sure the Plastic companionway cover is installed then take the old pieces of wood you have re-varnished and install them with Marine Grade Silicone Sealant. I didn’t cut any wood away around the drain holes as it was really close to clearing. I just made sure I put some Sealant on the wood near the hole. Then you can take the Slat and measure it, I just put it in, slid the top till it touched the slat and then took a pen and drew a line on the slat. I then took it home and cut it on my table saw. Once this is finished you are done. Good work and I hope this helped some.

Here are some pictures of the completed (well except the gelcoat outside) project.

If you want bigger shots just let me know and I can email them to you.

Ben Braden